Compare Version Numbers -- leetcode

Compare two version numbers version1 and version2.

If version1 > version2 return 1, if version1 < version2 return -1, otherwise return 0.

You may assume that the version strings are non-empty and contain only digits and the . character.

The . character does not represent a decimal point and is used to separate
number sequences.

For instance, 2.5 is not "two and a half" or "half way to version three",
it is the fifth second-level revision of the second first-level revision.

Here is an example of version numbers ordering:

0.1 < 1.1 < 1.2 < 13.37

基本思路：

转换成整数再作比较。

class Solution {
public:
    int compareVersion(string version1, string version2) {
        int i=0, j=0;
        while (i<version1.size() || j<version2.size()) {
            int num1 = 0;
            while (i<version1.size() && version1[i] != '.') {
                num1 = num1 * 10 + version1[i]-'0';
                ++i;
            }

            int num2 = 0;
            while (j<version2.size() && version2[j] != '.') {
                num2 = num2 * 10 + version2[j] - '0';
                ++j;
            }

            ++i;
            ++j;

            if (num1 != num2)
                return num1 > num2 ? 1 : -1;
        }

        return 0;
    }
};